Synthesis of aliphatic alcohols as aroma chemicals

ABSTRACT

The present invention relates to a method for preparing a compound of formula (I). The present invention also relates to compounds of formula (A) or a compound in the form of a stereoisomer. The present invention further relates to the use of a compound of formula (A) as aroma chemical.

FIELD OF THE INVENTION

The present invention relates to a method for preparing a compound offormula (I). The present invention also relates to compounds of formula(A) or a compound in the form of a stereoisomer. The present inventionfurther relates to the use of compound of formula (A) as aroma chemical.

BACKGROUND OF THE INVENTION

DE 1,311,600 describes a process for the preparation of a mixture ofracemic 6-ethyl-2-methyl-octen-(5)-ol-(1) and6-ethyl-2-methyl-octen-(6)-of-(1) starting from diethyl ketone. Here,the di-ethyl ketone is condensed with a mixture of cis- andtrans-penten-(2)-yn-(4)-ol-(1) in the presence of potassium hydroxide toget a mixture of cis- and trans-6-ethyl-octen-(2)-yne-(4)-diol-(1,6)which is hydrogenated in the presence of hydrogen and Raney-Ni to get6-ethyl-octanediol-(1,6). The saturated diol is dehydrated in thepresence of potassium bisulfate at a temperature of 150° -160° C. toresult in a crude mixture of cis- and trans-6-ethyl-octen-(5)-ol-(1) and6-ethyl-octen-(6)-ol-(1) after repeated washings with sodium carbonatesolution and water. The mixture of cis- andtrans-6-ethyl-octen-(5)-ol-(1) and 6-ethyl-octen-(6)-ol-(1) is furtherreacted with sodium methylate in the presence of zinc oxide to give amixture of 6-ethyl-2-methyl-octen-(5)-ol-(1) and6-ethyl-2-methyl-octen-(6)-of-(1). This synthesis would not appear to bevery suitable for an industrial process on account of tedious work-upprocedures and low yields.

The preparation of (6E)-3,6-dimethyloct-6-en-1-ol and(6Z)-3,6-dimethyloct-6-en-1-ol is achieved by EP 1,029,841 B1 byreaction of the Grignard reagent of THP-protected5-bromo-3-methylpentan-1-ol with acetaldehyde, subsequent Dess-Martinoxidation, followed by Wittig re-action with ethyl triphenyl phosphoniumbromide and acid-catalysed deprotection.

The present invention relates to a process for the preparation ofaliphatic alcohols as aroma chemicals. It is an object of the presentinvention to decrease or minimize the number of reaction steps forpreparation of aliphatic alcohols without impairing the yield. It isalso an object of the present invention to provide a flexibility ofpreparing various substituted aliphatic alcohols without furtherincrease in the number of steps. The present invention also relates tocompounds of formula (A) or a compound in the form of a stereoisomer.The present invention further relates to the use of compound of formula(A) as aroma chemical.

SUMMARY OF THE INVENTION

The inventors have surprisingly found that this object is achieved, andthe present invention process has the following advantages:

-   -   The process is viable on industrial scale.    -   The modification of substituents on the aliphatic alcohol chain        is carried out without increasing the number of steps or        impairing the yield.    -   Since protecting groups usually increase the number of steps of        a synthesis and increase the amount of waste generated, the        present invention process sequence does not use any protecting        groups.

Hence, the invention provides a method for preparing a compound offormula (I)

wherein

is a single or a double bond,

wherein formula (I) comprises

the compound of the formula (Ia)

the compound of the formula (Ib)

and

the compound of the formula (Ic)

and stereoisomers thereof;

whereby m is 0; R¹, R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

whereby m is 1, 2 or 3; R¹, R², R³, R⁴ and R⁵, identical or different,are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl;

comprising at least the steps of:

a) providing a compound of formula (IIa),

whereby m is 0; R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; whereby mis 1, 2 or 3 and R², R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

b) subjecting the compound of the formula (IIa) to a compound selectedfrom peroxyacids and peroxides to obtain a compound of formula (IIb),

-   -   c) reacting the compound of the formula (IIb) with a compound of        formula (IIc),

R¹CH₂MgX

formula (11c),

wherein R¹ is selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl; X is Cl, Br or I, to obtain a compound of formula(11d),

whereby m is 0; R¹, R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

whereby m is 1, 2 or 3 and R¹, R², R³, R⁴ and R⁵, identical ordifferent, are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl;

-   -   d) subjecting the compound of formula (IId) to a dehydration        reaction to obtain the compound of the formula (I).

In a preferred embodiment, the invention provides a method for preparinga compound of formula (I′)

wherein

is a single or a double bond,

wherein formula (I′) comprises

the compound of the formula (Ia′)

the compound of the formula (Ib′)

the compound of the formula (Ic′)

and

stereoisomers thereof;

wherein R¹, R², R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H,

-   -   C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

comprising at least the steps of:

-   -   a) providing a compound of formula (IIa′)

wherein R², R³, R⁴ and R⁵, identical or different, are selected from thegroup consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

b) subjecting the compound of the formula (IIa) to a compound selectedfrom peroxyacids and peroxides to obtain a compound of formula (IIb′),

c) reacting the compound of the formula (IIb′) with a compound offormula (IIc′),

R¹CH₂MgX

formula (IIc′)

wherein R¹ is selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl; X is Br, Cl or I, to obtain a compound of formula(IId′),

wherein R¹, R², R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

d) subjecting the compound of formula (lid') to a dehydration reactionto obtain the compound of the formula (I′).

The invention further provides a compound of the formula A

wherein

is a single or a double bond,

wherein formula A comprises the compound of the formula (A.a),

the compound of the formula (A.b),

and

the compound of the formula (A.c)

wherein R¹, R² and R⁵, identical or different, are selected from thegroup consisting of H,

C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

R⁴ is selected from the group consisting of H, C₂-C₄-alkyl andC₃-C₄-cycloalkyl;

R³ is H;

and stereoisomers thereof, with a proviso that at least one of the R¹,R², R⁴ and R⁵ is not H.

The invention further relates to a composition comprising at least onecompound selected from the compound of the formula A, preferably themixture of compounds of the formulae (A.a),

(A.b) and (A.c). The invention also relates to the use of a compound ofthe formula A as aroma chemical.

DESCRIPTION OF THE INVENTION

In one embodiment, the invention provides a method for preparing acompound of formula (I)

wherein

is a single ora double bond,

wherein formula (I) comprises

the compound of the formula (Ia)

the compound of the formula (Ib)

and

the compound of the formula (Ic)

and stereoisomers thereof;

whereby m is 0; R¹, R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

whereby m is 1, 2 or 3; R¹, R², R³, R⁴ and R⁵, identical or different,are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl;

comprising at least the steps of:

a) providing a compound of formula (IIa),

whereby m is 0; R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; whereby mis 1, 2 or 3 and R², R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

b) subjecting the compound of the formula (IIa) to a compound selectedfrom peroxyacids and peroxides to obtain a compound of formula (IIb),

c) reacting the compound of the formula (IIb) with a compound of formula(IIc),

R¹CH₂MgX

formula (11c),

wherein R¹ is selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl, to obtain a compound of formula (IId),

whereby m is 0; R¹, R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;whereby m is 1, 2 or 3 and R¹, R², R³, R⁴ and R⁵, identical ordifferent, are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl;

d) subjecting the compound of formula (IId) to a dehydration reaction toobtain the compound of the formula (I).

Although the present invention will be described with respect toparticular embodiments, this description is not to be construed in alimiting sense.

Before describing in detail exemplary embodiments of the presentinvention, definitions important for understanding the present inventionare given. As used in this specification and in the appended claims, thesingular forms of “a” and “an” also include the respective pluralsunless the context clearly dictates otherwise. In the context of thepresent invention, the terms “about” and “approximately” denote aninterval of accuracy that a person skilled in the art will understand tostill ensure the technical effect of the feature in question. The termtypically indicates a deviation from the indicated numerical value of±20%, preferably ±15%, more preferably ±10%, and even more preferably±5%. It is to be understood that the term “comprising” is not limiting.For the purposes of the present invention the term “consisting of” isconsidered to be a preferred embodiment of the term “comprising of”.

In a preferred embodiment, the invention provides a method for preparinga compound of formula (I′)

wherein

is a single or a double bond,

wherein formula (I′) comprises

the compound of the formula (Ia′)

the compound of the formula (Ib′)

and

the compound of the formula (Ic′)

and stereoisomers thereof;

wherein R¹, R², R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

comprising at least the steps of:

a) providing a compound of formula (IIa′),

wherein R², R³, R⁴ and R⁵, identical or different, are selected from thegroup consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

b) subjecting the compound of the formula (IIa) to a compound selectedfrom peroxyacids and peroxides to obtain a compound of formula (IIb′),

c) reacting the compound of the formula (IIb′) with a compound offormula (IIc′),

R¹CH₂MgX

formula (IIc′),

wherein R¹ is selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl; X is Br, Cl or I, to obtain a compound of formula(IId′),

wherein R¹, R², R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

d) subjecting the compound of formula (IId′) to a dehydration reactionto obtain the compound of the formula (I′).

In another embodiment, the process steps (b), (c) and (d) and/or steps(b) and (c) and/or steps (c) and (d) are carried out in a single pot.

In yet another embodiment, the peroxyacid in step b) is selected fromthe group consisting of peroxymonosulfuric acid, peroxyphosphoric acid,peroxyacetic acid, peroxyformic acid, peroxytrifluoroacetic acid,potassium peroxymonosulfate, sodium perborate, peroxynitric acid andperoxybenzoic acid. In a preferred embodiment, the peroxybenzoic acid ismetachloroperoxybenzoic acid.

In yet another preferred embodiment, the peroxide in step b) is hydrogenperoxide. In a preferred embodiment, the temperature in step b) is inthe range of 0° C. to 70° C., in particular, the temperature is in therange of 20° C. to 60° C.

In another embodiment, in step b) the molar ratio of the compoundselected from peroxyacids and peroxides to the compound of formula (IIa)is in the range of ≥1 to ≤3.0, in particular, in the range of ≥1.1 to≤2.0.

In another preferred embodiment, in step c) the temperature is in therange of ≥−20° C. to ≤50° C., preferably, the temperature is in therange of ≥0° C. to ≤20° C.

In yet another embodiment, in step c) the molar ratio of the compound offormula (IIc) to the compound of formula (IIb) is in the range of ≥2 to≤5.0, in particular, in the range of ≥2.5 to ≥5.0.

In an embodiment, the step d) is carried out in the presence of an acid,particularly, the acid is selected from the group consisting ofmethanesulfonic acid, phosphoric acid, p-toluenesulfonic acid, formicacid, sulfuric acid, hydrochloric acid and acetic acid, preferably,p-toluenesulfonic acid, more preferably, methanesulfonic acid.

In another embodiment, in step d) the temperature is in the range of ≤0°C. to ≥80° C., preferably, in the range of ≤10° C. to ≥40° C.

In yet another embodiment, in step d) the molar ratio of the acid to thecompound of formula (IIc) is in the range of ≤0.2 to ≥4.0, inparticular, in the range of ≤0.2 to ≥2.5.

In one embodiment, the present invention provides a compound of theformula A

wherein

is a single or a double bond,

wherein formula A comprises

the compound of the formula (A.a),

the compound of the formula (A.b),

and

the compound of the formula (A.c)

wherein R¹, R² and R⁵, identical or different, are selected from thegroup consisting of H,

C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

R⁴ is selected from the group consisting of H, C₂-C₄-alkyl andC₃-C₄-cycloalkyl;

R³ is H;

and stereoisomers thereof, with a proviso that at least one of the R¹,R², R⁴ and R⁵ is not H.

In preferred embodiment, R¹ is H or methyl and R³ is H.

In yet another preferred embodiment, R² and R⁵, identical or different,are selected from the group consisting of H, methyl, ethyl, 1-propyl,1-methylethyl, and cyclopropyl.

In particular, R² is H or methyl. More preferably, R⁵ is methyl or1-methylethyl.

In one embodiment, the present invention provides a compound of theformula A

wherein

is a single or a double bond,

wherein formula A comprises

the compound of the formula (A.a),

the compound of the formula (A.b),

and

the compound of the formula (A.c)

wherein R¹, R² and R⁵, identical or different, are selected from thegroup consisting of H,

C₁-C₄-alkyl and C₃-C₄-cycloalkyl;

R⁴ is selected from the group consisting of H, C₂-C₄-alkyl andC₃-C₄-cycloalkyl; R³ is H;

and stereoisomers thereof, with a proviso that when R¹ is H or methylthen at least one of the R², R⁴ and R⁵ is not H.

In preferred embodiment, the present invention provides the compound offormula A, wherein R¹ is H or methyl; R² is selected from the groupconsisting of H, methyl, ethyl, 1-propyl, 1-methylethyl, andcyclopropyl; R⁵ is selected from the group consisting of methyl, ethyl,1-propyl, 1-methylethyl, and cyclopropyl; R⁴ is selected from the groupconsisting of H, ethyl, 1-propyl, 1-methylethyl, and cyclopropyl; and R³is H.

In yet another preferred embodiment, R⁴ is selected from the groupconsisting of H, ethyl, 1-propyl, 1-methylethyl, and cyclopropyl;

In preferred embodiment, the compound of formula A is selected from thecompounds of formulae (A.a2), (A.b2), (A.c2), (A.a3), (A.b3) and (A.c3).

and stereoisomers thereof.

In one embodiment, the present invention relates to a compositioncomprising at least one compound selected from the compound of theformula A, preferably the mixture of compounds of the formulae (A.a),(A.b) and (A.c).

In a preferred embodiment, the compositions according to the inventioncomprise at least two compounds selected from the compounds of theformulae A, preferably the mixture of compounds of the formulae (A.a),(A.b) and (A.c).

In another embodiment, the present invention relates to the use of acompound of the formula A or of a composition comprising at least onecompound selected from the compound of the formula A, preferably themixture of compounds of the formulae (A.a), (A.b) and (A.c), as aromachemical.

In preferred embodiment, the present invention relates to the use of acompound of the formula A, preferably the mixture of compounds of theformulae (A.a), (A.b) and (A.c), as aroma chemical.

In yet another embodiment, the present invention relates to the use of acompound of the formula A or of a composition comprising at least twocompounds selected from the compound of formula A, more preferably themixture of compounds of the formulae (A.a), (A.b) and (A.c), as aromachemical.

In yet another embodiment, the present invention relates to the use asaroma chemical, wherein i) at least one compound selected from thecompound of formula A, preferably from the compounds of the formulae(A.a1), (A.b1) and (A.c1), is used for preparing a fragrance and/oraroma having a note of muguet and/or rose,

and/or

ii) at least one compound selected from the compound of formula A,preferably from the compounds of the formulae (A.a2), (A.b2) and (A.c2),is used for preparing a fragrance and/or aroma having a note of roseand/or muguet,

and/or

iii) at least one compound selected from the compound of formula A,preferably from the compounds of the formulae (A.a3), (A.b3) and (A.c3),is used for preparing a fragrance and/or aroma having a note of woodyand/or dusty

In a preferred embodiment, the present invention relates to the use asaroma chemical, wherein

i) the compound of the formula A, preferably mixture of compounds of theformulae (A.a1),

(A.b1) and (A.c1), is used for preparing a fragrance and/or aroma havinga note of muguet and/or rose,

and/or

ii) the compound of the formula A, preferably mixture of compounds ofthe formulae (A.a2), (A.b2) and (A.c2), is used for preparing afragrance and/or aroma having a note of rose and/or muauet.

and/or

iii) the compound of the formula A, preferably mixture of compounds ofthe formulae (A.a3),

(A.b3) and (A.c3), is used for preparing a fragrance and/or aroma havinga note of woody and/or dusty

In yet another preferred embodiment, the present invention relates tothe use of a compound, selected from compound of the formulae (A.a),(A.b) and (A.c) or of a composition of at least two compounds selectedfrom compounds of the formulae (A.a), (A.b) and (A.c), as aromachemical.

In a preferred embodiment, the use of compound of formula A, as aromachemical in compositions selected from perfumes, detergents and cleaningcompositions, cosmetic agents, body care agents, hygiene articles,products for oral and dental hygiene, scent dispensers, fragrances andpharmaceutical agents. In particular, the use of mixture of (A.a), (A.b)and (A.c) in compositions selected from perfumes, detergents andcleaning compositions, cosmetic agents, body care agents, hygienearticles, products for oral and dental hygiene, scent dispensers,fragrances and pharmaceutical agents.

In a preferred embodiment, the present invention relates to an aromasubstance and/or fragrance composition comprising

i) at least a compound of formula (A) or a composition comprising atleast one compound selected from the compound of formula A, preferablythe mixture of compounds of the formulae (A.a), (A.b) and (A.c),

ii) optionally at least one further aroma chemical different from thecomponent i), and

iii) optionally at least one diluent, with the proviso that thecomposition comprises at least one component ii) or iii).

In one embodiment, the present invention relates to a perfumed orfragranced product comprising at least a compound of formula (A) or acomposition comprising at least one compound selected from the compoundof formula A, preferably the mixture of compounds of the formulae (A.a),(A.b) and (A.c).

In yet another preferred embodiment, the present invention relates to amethod for scenting a product, particularly for imparting and/orenhancing an odor or flavor, in which at least one compound of formula(A) is used and/or in which a composition comprising at least onecompound selected from the compound of formula A, preferably the mixtureof compounds of the formulae (A.a), (A.b) and (A.c) is used.

Compounds can be characterized e.g. by Nuclear magnetic resonancespectroscopy (NMR), and/or by Gas Chromatography (GC).

SYNTHESIS EXAMPLES Example 1 Preparation of6-ethyl-3-methyl-oct-6-en-1-ol

Step-1: 5-methyloxepan-2-one

To the solution of 4-methyl cyclohexanone (50 g, 0.45 mol) in 300 mLdichloromethane (DCM), was added a solution of meta-chloro-perbenzoicacid (mCPBA, ˜77%, 130 g, 0.58 mol) in 1 L DCM at 20° C. in 1 h.Stirring was continued at RT for 2 h and the reaction was monitored byGC. After 2 h, GC showed complete conversion of the starting material.The precipitated solid was filtered off and the filtrate was washed withthiosulfate solution followed by bicarbonate solution. The organic phasewas dried and the solvent evaporated to obtain 53 g of product (lactone)having GC purity of 98%. Yield 90%.

Step-2: 6-ethyl-3-methyl-octane-1,6-diol

To the cooled solution of ethyl magnesium bromide (500 mL, 1.75 mol) at0-5° C. in a 3-necked flask was added a solution of 45 g (0.35 mol) ofthe lactone from the previous step in 50 mL dry

THF under N2 atmosphere. After 30 min, the addition was complete and thereaction mixture was allowed to come to RT and was stirred for 2 h. TLCconfirmed the completion of the reaction. Then, the reaction wasquenched with 800 mL saturated ammonium chloride solution and extractedwith ethyl acetate (3×500 mL). The combined organic layer was washedwith brine, dried over sodium sulfate and the solvent was evaporated toobtain 58 g crude product which was the tertiary-alcohol having GCpurity of 99%. Yield 87%.

Step-3: 6-ethyl-3-methyl-oct-6-en-1-ol

A solution of the tertiary alcohol from the previous step (75 g, 0.40mol) and para-toluene sulfonic acid (pTSA, 17 g, 0.089 mol) in 500 mLethylene dichloride was stirred at 60° C. The reaction was monitored byTLC which showed complete disappearance of the starting material after 7h. The reaction was quenched with bicarbonate solution and the phasesseparated. The organic layer was dried and the solvent was evaporated toget 65 g of the product having GC purity of 75%. Yield 72%.

Example 2 Preparation of 6-ethyl-2-methyl-oct-6-en-1-ol

Step-1: 6-methyloxepan-2-one

Added the solution of 3-methyl-cyclohexanone (20 g, 0.18 mol) in 200 mLDCM to the stirred suspension of mCPBA (˜77%, 48.2 g, 0.21 mol) andNaHCO3 (18 g, 0.21 mol) in 200 mL DCM. Stirred at RT for 6 h. Then, thereaction was stopped by addition of 30 mL saturated aq. KI solutionfollowed by bisulfite solution. Separated the layers, washed the organiclayer with water and dried. The solvent was evaporated to get a thickcolorless liquid (21.5 g) having GC purity of about 90%. Yield 84%.

Step-2: 6-ethyl-2-methyl-octane-1,6-diol

A solution of the lactone from the previous step (4.5 g, 0.035 mol) in30 mL THF was added dropwise to the solution of 1 M ethyl magnesiumbromide (175 mL, 0.175 mol) in THF at 5-10° C. under N2 atmosphere.After complete addition, the reaction mixture was brought to RT andstirred for 3 h. Then, the reaction was quenched with cold sat. NH4Clsolution (100 mL) and extracted with ethyl acetate (2×50 mL). Thecombined organic layer was dried and the solvent was evaporated to get 6g of the crude 6-ethyl-2-methyl-octane-1,6-diol having GC purity 90%.Yield 82%.

Step-3: 6-ethyl-2-methyl-oct-6-en-1-ol

To the solution of the tertiary alcohol from the previous step (6 g,0.032 mol) in 50 mL DCM was added methane sulfonic acid in 10 min. Thereaction mixture was stirred for 3 h and then quenched with bicarbonatesolution. The phases were separated and the organic layer was washedwith water and dried. The solvent was evaporated to get 5 g of crudedehydrated product (crude yield 92%). This was further purified bycolumn chromatography to get 2 g of product having a purity of 98%.

Example 3 Preparation of 7-ethylnon-7-en-2-ol

Step-1: 7-methyloxepan-2-one

To a solution of 2-methyl-cyclohexanone (5 g, 0.045 mol) in 50 mL DCMwas added a solution of mCPBA (˜77%, 16 g, 0.072 mol) in 100 mL DCM at20° C. over a period of 30 min. The reaction mixture was stirred at RTfor 5 h. The precipitate was filtered off and the filtrate was washedwith thiosulfate solution followed by bicarbonate solution. The organiclayer was dried and the solvent evaporated to get 5.1 g crude lactonehaving GC purity >98%. Yield 87%.

Step-2: 7-ethylnonane-2,7-diol

The solution of the lactone from the previous step (3 g, 0.023 mol) in20 mL THF was added dropwise to the solution of ethyl magnesium bromide(1 M in THF, 120 mL, 0.12 mol) at 10-20° C. under N2 atmosphere. Aftercomplete addition, the reaction mixture was brought to RT and stirredfor 4 h. Then, the reaction was quenched with 2 N HCl (50 mL) andextracted with MTBE (2×50 mL). The combined organic layer was dried andthe solvent was evaporated to get 4 g crude alcohol having GCpurity >90%. Yield 83%.

Step-3: 7-ethylnon-7-en-2-ol

To the solution of the alcohol from the previous step (4 g, 0.021 mol)in 70 mL Dichloroethane was added pTSA (0.6 g, 0.00324 mol). Thereaction mixture was heated to 60° C. and stirred at this temperaturefor 3 h, before it was quenched with bicarbonate solution. The layerswere separated and the organic layer was washed with water and dried.The solvent was evaporated to get 3.4 g crude dehydrated product (crudeyield 95%). This was further purified by column chromatography to get1.2 g of product having a purity of 98%.

Example 4 Preparation of 8-ethyl-2,6-dimethyl-dec-8-en-3-ol

Step-1: 7-isopropyl-4-methyl-oxepan-2-one

To a solution of menthone (10 g, 0.065 mol) in 60 mL DCM was added asolution of mCPBA (˜77%, 26 g, 0.116 mol) in 200 mL DCM at 20° C. over aperiod of 30 min. The reaction mixture was stirred at RT for 18 h. Then,the reaction mixture was washed with thiosulfate solution followed bybicarbonate solution. The organic layer was dried and the solvent wasevaporated to get 11 g of crude lactone having GC purity of 97%. Yield96%.

Step-2: 8-ethyl-2,6-dimethyl-decane-3,8-diol

To a solution of ethyl magnesium bromide (1 M in THF, 88 mL, 0.088 mol)was added the lactone from the previous step (3 g, 0.018 mol) in 25 mLTHF dropwise at 5-10° C. under N2 atmosphere. After complete addition,the reaction mixture was brought to RT and stirred for 1.5 h. Then, thereaction was quenched with sat. NH4Cl solution and extracted with ethylacetate (2×50 mL). The combined organic layer was dried and the solventwas evaporated to get 4 g crude tertiary alcohol having GC purity of 88%(crude yield 85%). It was purified by column chromatography to get 2 gof product of GC purity 98%.

Step-3: 8-ethyl-2,6-dimethyl-dec-8-en-3-ol

To the solution of the alcohol from the previous step (6 g, 0.026 mol)in 20 mL DCM cooled to 10-20° C. was added 0.5 mL methane sulfonic acidand the reaction mixture was stirred at RT for 3 h. Then, the reactionwas quenched with bicarbonate solution and the layers were separated.The organic layer washed with water and dried and the solvent wasevaporated to get 5 g of crude dehydrated product. This was purified bycolumn chromatography and obtained as two fractions: Fraction-1:2 g,GC=95% and fraction-2: 2 g, GC =90%. Yield 67%.

1. A method for preparing a compound of formula (I)

wherein

is a single or a double bond, wherein formula (I) comprises the compoundof the formula (Ia)

the compound of the formula (Ib)

the compound of the formula (Ic)

and stereoisomers thereof; whereby m is 0; R¹, R³, R⁴ and R⁵, identicalor different, are selected from the group consisting of H, C₁-C₄-alkyland C₃-C₄-cycloalkyl; whereby m is 1, 2 or 3 and R¹, R², R³, R⁴ and R⁵,identical or different, are selected from the group consisting of H,C₁-C₄-alkyl and C₃-C₄-cycloalkyl; comprising at least the steps of: a)providing a compound of formula (IIa),

whereby m is 0; R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; whereby mis 1, 2 or 3; R2, R3, R4 and R5, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; b)subjecting the compound of the formula (IIa) to a compound selected fromperoxyacids and peroxides to obtain a compound of formula (IIb),

c) reacting the compound of the formula (IIb) with a compound of formula(IIc),R¹CH₂MgXformula (IIc), wherein R¹ is selected from the group consisting of H,C₁-C₄-alkyl and C₃-C₄-cycloalkyl; X is Br, Cl or I, to obtain a compoundof formula (IId),

whereby m is 0; R¹, R³, R⁴ and R⁵, identical or different, are selectedfrom the group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl;whereby m is 1, 2 or 3 and R¹, R², R³, R⁴ and R⁵, identical ordifferent, are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl; d) subjecting the compound of formula (IId) to adehydration reaction to obtain the compound of the formula (I).
 2. Themethod of claim 1 for preparing compound of formula (I′)

wherein

is a single or a double bond, wherein formula (I′) comprises thecompound of the formula (Ia′)

the compound of the formula (Ib′)

and the compound of the formula (Ic′)

and stereoisomers thereof; wherein R¹, R², R³, R⁴ and R⁵, identical ordifferent, are selected from the group consisting of H, C₁-C₄-alkyl andC₃-C₄-cycloalkyl; comprising at least the steps of: a) providing acompound of formula (IIa′),

wherein R², R³, R⁴ and R⁵, identical or different, are selected from thegroup consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; b) subjectingthe compound of the formula (IIa′) to a compound selected fromperoxyacids and peroxides to obtain a compound of formula (IIb′),

c) reacting the compound of the formula (IIb′) with a compound offormula (IIc′),R¹CH₂MgXformula (IIc′), wherein R¹ is selected from the group consisting of H,C₁-C₄-alkyl and C₃-C₄-cycloalkyl; X is Br, Cl or I, to obtain a compoundof formula (IId′),

wherein R¹, R², R³, R⁴ and R⁵, identical or different, are selected fromthe group consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; d)subjecting the compound of formula (IId') to a dehydration reaction toobtain the compound of the formula (I′).
 3. The process according to theclaim 1, wherein steps (b), (c) and (d) and/or steps (b) and (c) and/orsteps (c) and (d) are carried out in a single pot.
 4. The processaccording to the claim 1, wherein the peroxyacid in step b) is selectedfrom the group consisting of peroxymonosulfuric acid, peroxyphosphoricacid, peroxyacetic acid, peroxyformic acid, peroxytrifluoroacetic acid,potassium peroxymonosulfate, sodium perborate, peroxynitric acid andperoxybenzoic acid.
 5. The process according to the claim 4, wherein theperoxybenzoic acid is meta-chloroperoxybenzoic acid.
 6. The processaccording to the claim 1, wherein the peroxide in step b) is selectedfrom the group consisting of hydrogen peroxide.
 7. The process accordingto claim 1, wherein step d) is carried out in the presence of an acid.8. The process according to claim 7, wherein the acid is selected fromthe group consisting of methanesulfonic acid, phosphoric acid,p-toluenesulfonic acid, formic acid, sulfuric acid, hydrochloric acidand acetic acid.
 9. A compound of the formula A

wherein

is a single or a double bond, wherein formula A comprises the compoundof the formula (A.a),

the compound of the formula (A.b),

the compound of the formula (A.c)

wherein R¹, R² and R⁵, identical or different, are selected from thegroup consisting of H, C₁-C₄-alkyl and C₃-C₄-cycloalkyl; R⁴ is selectedfrom the group consisting of H, C₂-C₄-alkyl and C₃-C₄-cycloalkyl; R³ isH; and stereoisomers thereof, with a proviso that when R¹ is H or methylthen at least one of the R², R⁴ and R⁵ is not H.
 10. The compound ofclaim 9, wherein R¹ is H or methyl; R² is selected from the groupconsisting of H, methyl, ethyl, 1-propyl, 1-methylethyl, andcyclopropyl; R⁵ is selected from the group consisting of methyl, ethyl,1-propyl, 1-methylethyl, and cyclopropyl; R⁴ is selected from the groupconsisting of H, ethyl, 1-propyl, 1-methylethyl, and cyclopropyl; and R³is H.
 11. The compound of according to claim 9, selected from thecompounds of formulae (A.a2), (A.b2), (A.c2), (A.a3), (A.b3) and (A.c3).

and stereoisomers thereof.
 12. A composition comprising at least onecompound selected from the the mixture of compounds of the formulae(A.a), (A.b) and (A.c) according to claim
 9. 13. Use of the compound ofthe formula A according to claim 9 as aroma chemical.
 14. The useaccording to claim 13, wherein i) the at least one compound selectedfrom the compound of the from the compounds of the formulae (A.a1),(A.b1) and (A.c1), is used for preparing a fragrance and/or aroma havinga note of muguet and/or rose,

and/or ii) the at least one compound selected from the compound of theformulae (A.a2), (A.b2) and (A.c2), is used for preparing a fragranceand/or aroma having a note of rose and/or muguet,

and/or iii) the at least one compound selected from the compound of theformulae (A.a3), (A.b3) and (A.c3), is used for preparing a fragranceand/or aroma having a note of woody and/or dusty


15. The use according to claim 14, wherein i) the compound of theformulae (A.a1), (A.b1) and (A.c1), is used for preparing a fragranceand/or aroma having a note of muguet and/or rose,

and/or ii) the compound of the formulae (A.a2), (A.b2) and (A.c2), isused for preparing a fragrance and/or aroma having a note of rose and/ormuguet,

and/or iii) the compound of the formulae (A.a3), (A.b3) and (A.c3), isused for preparing a fragrance and/or aroma having a note of woodyand/or dusty


16. The use according to claim 13 in compositions selected fromperfumes, detergents and cleaning compositions, cosmetic agents, bodycare agents, hygiene articles, products for oral and dental hygiene,scent dispensers, fragrances and pharmaceutical agents.
 17. An aromasubstance and/or fragrance composition comprising i) at least a compoundof the formula (A) according to claim 9, ii) optionally at least onefurther aroma chemical different from the component i), and iii)optionally at least one diluent, with the proviso that the compositioncomprises at least one component ii) or iii).
 18. A perfumed orfragranced product comprising at least a compound of the formula (A)according to claim
 9. 19. A method for scenting a product, in which atleast one compound of the formula (A) according to claim 9 is used.